Cathepsin H (CTSH), which can act both as an aminopeptidase and as an endopeptidase, is a lysosomal cysteine protease of the papain family. CTSH is composed of a dimer of disulfide-linked heavy and light chains, both produced from a single protein precursor. CTSH is associated with various pathological conditions like human fibrous meningioma, colorectal cancer, arthritis, human prostate tumor and lung cancer. CTSH is associated with cancer progression because of their ability to degrade extracellular matrices facilitating invasion, angiogenesis and metastasis as is evident from numerous clinical reports and experimental models. The expression of CTSH is significantly increased in disease states such as in prostate tumors, sera of asthmatic patients, and mucosa of colorectal cancer patients.